Scientists and government officials from all over the world are meeting in Geneva this week to consider how climate change impacts the land and how the lands and forests impact the climate.

Their detailed report will be released on Thursday.

However, researchers at development charity Christian Aid have put together a study showing how that climate change is now having a disproportionate impact on the food systems of the countries that have done least to produce the carbon emissions that are driving up temperatures.

Their study says that the top 10 most food insecure countries all generate less than half a tonne of CO2 per person, and in total just 0.08% of global emissions.

"Our research shows that rising concentrations of CO2 in the atmosphere are reducing the nutritional quality of the food we eat and that the most vulnerable people to these impacts are those least responsible for rising global CO2 concentrations," said Dr Samuel Myers, principal research scientist at Harvard University's department of environmental health.

"From this, and other research, what is quite clear is that climate change is not only a global health crisis, it is a moral crisis."

Other researchers say that the report on food insecurity is a warning for rich and poor alike, that climate change is having profound effects on our ability to feed the planet.

"These are warning signals that all of us ignore at our peril, for agriculture ultimately is one of the most threatened of our economic sectors and most fundamental for the healthy functioning of our societies and our communities," said Dr Doreen Stabinsky, professor of global environmental politics at the College of the Atlantic in Maine, US, who was not involved with the study.

"Both the Christian Aid report and the upcoming IPCC Special Report on Climate Change and Land begin to make clear how serious a threat this is, and how urgently we need to act."